public class DVDplayer {
    //使用单例模式, 使用饿汉式
    private static DVDplayer instance = new DVDplayer();
    private DVDplayer(){
        //防止外部进行初始化
    }
    public static DVDplayer getInstanc() {
        return instance;
    }
    public void on() {
        System.out.println(" dvd on ");
    }
    public void off() {
        System.out.println(" dvd off ");
    }
    public void play() {
        System.out.println(" dvd is playing ");
    }
    public void pause() {
        System.out.println(" dvd pause ..");
    }
}

//等等各种设备的启动

